Thanks for the reply and rechecking the uploaded files. :)
I just waited for the new GPU driver version to release to retry playing the game in VR mode. Unfortionately all the above stated problems stayed.
I have an RTX3090 and tried both available driver versions: Studio (the more stable one) and Game (the one with cutting edge features)
and also different quality settings. It really can't be the GPU or the installed drivers at this point. Also regarding that every other game runs perfectly fine (no matter, if VR or not).
I put the game on my NVME SSD to rule out "longer" loading times and checked my CPU, RAM and SSD usage while the game was running. My PC doesn't even barely start to sweat even with the highest quality settings.
I'm not experienced in Unity so this is a wild guess but maybe there is a missed out setting for the render mode (in regards to opacity or two sided mode?) or flipped normals in the character models? The Pubic hair and the censor/blur bar are reliably visible all times (along with the head) and I assume that both are simple planes/an alpha plane with a material assigned for which the direction of the planes normals may not matter?